(a) Field of the Invention
The present invention relates to a compact large-aperture photographic lens system and, more particularly, to a compact large-aperture photographic lens system for which the back focal length is long, intensity of light in the marginal portion is high and aperture ratio is Fl.2.
(B) Description of the Prior Art
A Gauss-type photographic lens systems with focal length of 50 mm, various lens systems are known. For most of them, however, the aperture ratio is about Fl.4. To reduce the weight of camera, it is necessary to obtain a compact lens system with short overall length. Moreover, it is generally required to make the back focal length long.
However, compact photographic lens systems with large aperture ratio and long back focal length are not yet known so much.